Hello,

I guess one could say that not all "MEMS cleanrooms" are created equal.

Cyrille's original question is from the point of view of what we like to
refer to here as CMOS-derived MEMS technologies/fabs, like ADI's
accelerometer fab in Cambridge.  Whereas other fabs, like ours, or maybe IMT
in California, are originally based on non-CMOS technologies.

So, in our fab for example, gold, copper, nickel, nickel-iron, and a slew of
other specialized metals (some are magnetic and some not) are commonplace.
We use them to build a competitive product beyond what a standard CMOS/MEMS
house might be able to offer.

And, we still have the technology to successfully run these processes on top
of CMOS wafers from our partner fabs.  It just takes the know-how of what
can and cannot be done to a wafer once it has CMOS circuitry and gold traces
on it.  Generally, we have characterized products and done full reliability
quals on a CMOS product after processing the front side with both copper and
gold and not incurred any ill effects from doing so, once we had established
a functional process to accomplish it.  Different CMOS-like technologies
might respond differently, though, I suppose, and some companies may
consider it a competitive advantage as to just how to deal with such wafers
in their fabs.

But for Cyrille's original inquiry, she could try an amazon.com search for
the title "Metal Impurities in Silicon-Device Fabrication (Springer Series
in Materials Science, Vol 24)" for a discussion of transition metals and
issues with their contamination of CMOS/silicon processes.

- Justin

Justin C. Borski
MEMS Program Manager
Advanced MicroSensors Inc.
jborski@advancedmicrosensors.com




-----Original Message-----
From: Cain, Mike [mailto:Mike.Cain@MEMSCAPINC.COM]
Sent: Tuesday, June 08, 2004 2:01 PM
To: General MEMS discussion
Subject: RE: [mems-talk] microelectronic compatible material


Just curious to know why a "MEMS cleanroom" should remain gold free?  I
know the obvious answer (Au contamination) but wonder why a MEMS fab
needs to be identical/compatable to CMOS fabs.  Seems limiting to me.

Regards,
Mike

-----Original Message-----
From: Cyrille Hibert [mailto:cyrille.hibert@nmrc.ie]
Sent: Tuesday, June 08, 2004 4:59 AM
To: mems-talk@memsnet.org
Subject: [mems-talk] microelectronic compatible material


Dear All,

In MEMS cleanroom people usually try to remain microlectronic compatible
(no gold...). Does anybody has a good reference to know which material
can be considered compatible with "standard" IC processing? What is
about Ni?

Regards,
Cyrille.

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